Centrifugal separator



June 24, 1958 J. STUART ll CENTRIFUGAL SEPARATOR 2 Sheets-Sheet 1 Filed July 6, 1955 JOSEPH 'sTuAin 11.

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AGENT.

June 24, 1958 J. STUART u CENTRIFUGAL SEPARATOR Filed July 6, 1955 I 2 Shets-Sheet 2 v JOSEPH STUART 11 INVENTOR.

- AGENT.

2,840,303 1C Patented June 24, 1958 2, 40,303 CENTRIFUGALJSEPARATOR Joseph Stuart II, Wilmington, Del., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware 7 Application July 6, 1955, Serial No. 520,267 12 Claims. (Cl. 233-28) This invention relates to the separation of liquids having different specific gravities by means of centrifugal force and more particularly relates to the separation of liquid explosive nitric esters from their reaction mixtures.

In accordance with the usual method of separating liquid explosive nitric esters from their reaction mixtures in either the batch or continuous process, a charge of a mixture of the ester and the spent acid is placed in a separator tank and allowed to stand until the spent acid and ester separates into two well defined layers. The heavier spent acid is then drained off through the bottom of the tank and sent to acid recovery and concentration procedures and the liquid nitric ester is then subjected to a prewash with sodium bicarbonate or equivalent and then sent to a neutralizer house Where the explosive oil is further washed and dried prior to use. In the currently popular Biazzi process it has been found possible to employ a continuous gravity type separator in which spent acid is continuously withdrawn from the bottom of the unit and liquid nitric ester from the top.

A more recent modification of the Biazzi process makes it possible to eliminate the soda prewash and to go immediately to the final sodawashes and emulsification step. In all of these prior art processes, however, there is an undesirably large amount of nitroglycerin'or other liquid explosive nitric ester present in the separator tank so that should an accident-occur, the amount of highly sensitive liquid explosive present is undesirably large. In the older batch processes, all of the liquid explosive nitric ester made in the entire charge is present in the separator tank and must be handled in this large amount up to the point of desensitization by emulsification. Even in a Biazzi process being run to satisfy the normal needs of a dynamite plant (2500 pounds of nitroglycerin per hour) there will always be between about 200 and 300 pounds of nitroglycerin in the system between the nitrator and the emulsifier. The presence of even this amount of liquid explosive nitric ester in the system is highly undesirable.

Now in accordance with the present invention, a means of separating liquid explosive nitric esters from'their reaction mixtures has been discovered which will produce the desired output but by which only a small fraction of the amount of liquid explosive is present in the system in shock sensitive state. -Genera'lly described the present invention is a centrifugal separator for liquids having in combination a bowl mounted to revolve about its vertical axis, means for revolving the bowl, and collecting means for the separated liquid components, the bowl comprising a receiving chamber at the top thereof for receipt of the liquid feed, a plurality of spaced passageways tending substantially horizontally inwardly and then substantially vertically downwardly, a plurality of spaced exit conduits for the heavier liquid component leading outwardly from the horizontal surface of the dam at points adjacent the intersection of the Wall of the separating chamber and the horizontal surface of the dam, and a plurality of spaced exit conduits for the lighter liquid component leading outwardly from the vertical surface of the dam at points adjacent the bottom of the extending downwardly and outwardly through the wall of the bowl from 'a point adjacent the intersection of the bottom and Wall of the receiving chamber, a separating chamber disposed below theireceiving chamber and in communication with the receiving chamber th'roughthe said passageways, a ,dam disposed at the bottom of the wall oithe separating chamber, and eX- separating chamber, said exit conduits for the liquid components being in communication with the said collecting means.

Preferably, the passageways leading downwardly and outwardly from the receiving chamber will empty into an annulus formed in the wall of the bowl, which annulus then leads downwardly and inwardly into the separating chamber. In either event, the wall of the separating chamber may be vertical or may be suitably inclined. Preferably, the Wall of the separating chamber will be inclined downwardly and outwardly.

If desired, the exit conduits for the heavier component may lead directly outwardly either horizontally or downwardly through the bowl and exit into the collecting means. is usually desirable to lead the heavier component initially downwardly and outwardly and then downwardly and in-' wardly into the bowl below the separating chamber and then provide other passageways which lead outwardly through the bowl at a point'sufficiently far below the dam to allow adequate spacing of the collecting means for the liquid components. It is a characteristic, however, of'all the embodiments of the present invention that the separator is self-draining and that if at any time the separator is shut down, any liquid separated or unseparated remaining in the separator will drain freely either into the collecting means or out the bottom of the separator. As will be more specifically illustrated in the preferred embodiments of the separator of the invention, the central portion of the bowl will be open and readily accessible for washing.

Having generally described the centrifugal separator" of the invention, more specific illustration of the prev ferred embodiments is presented in conjunction withthe drawing wherein like numerals refer to similar structural elements.

In the drawing Fig. 1 is a part elevational, part sec- 1 tional side viewof a complete device in accordance with the invention. Fig. 2 is a part sectional, partelevational view of a further embodiment of a receiving chamber in accordance with the invention. Fig. 3 is a part eleva-ntional, part sectional View of a receiving chamber containing a. preferred type of battling structure which en: hances the smoothness of flow. Fig. 4 is an enlarged f the device of' sectional View of the separation section of the invention.

In Fig. 1, a, centrifugal separator having a bowl 10 is supported by a support frame 11 and a shaft 12 whichis rotatably mounted in the support 11. A pulley 13 is see cured to the shaft 12 and is driven by means not shown by a V belt 14. The bowl 10 has an annular receiving chamber 15 into which the liquid feed is introduced through inlet pipe 16. Spaced passageways 17 are formed in the wall of the bowl 10 and lead downwardly and outwardly from holes 18 formed in the intersection of the The passageways empty into an annular groove 1 9 formed in wall and bottom of the receiving chamber 15.

the wall of the bowl 10 which leads downwardly and in-.-'

wardly into the separating chamber of the centrifuge.

The separating chamber has an outwardly inclined wall 20 which terminatesin a dam 21 which extends horizontally into the separating chamber and;t hen-vertically I downwardly tqflt e bo tom f ep a in .shambe However, as will be specifically illustrated, it

An exit annulus 22 is formed in the dam 21 adjacent the intersection of the wall 20 of the separating chamber and the horizontal surface 21 of the dam. Exit conduits 23 V for the heavier liquid component lead downwardly and outwardly to a point short of the outside surface of the bowl and then empty into communicating conduits 24 leading downwardly and inwardly into the interiorof the bowl below the separating chamber. Spaced exit conduits" 25 for the heavier component are formed in the wall of the bowl below the termination of the conduits 24 and empty into a collector 26 equipped with an exit nozzle 27. Spaced exit conduits 28 for the lighter liquid component are formed in the vertical surface of the dam 21 and extend downwardly and outwardly through the wall of the bowl andempty into a collector 29 equipped with an outlet nozzle 30. The bottom of the bowl 10 is sealed with a plastic plug 31, preferably of polyethylene or Teflon, which can be easily removed for inspection of the interior of the bowl. The collectors are supported on stools 32 which in turn rest upon a support member 33.

In Fig. 2 a receiving chamber is shown which. is equipped with plastic vanes or bafiles 40, preferably of Teflon. These vanes assist in the acceleration of the liquid feed prior to its exit from the receiving chamber through the holes 18 and passageways 17.

In Fig. 3 a receiving chamber is shown in which a bafile 50 is employed to prevent splashing of the feed as it is accelerated by the spinning bowl 10. The baffle 50 consists of a semicircular sheet extending 180 around the chamber 15. The baffie approaches the bottom of the chamber but is spaced therefrom by a narrow aperture 51. The liquid inlet 16 extends through the top of the baflle at. an angle and introduces the feed against. the battle. When the feed is introduced at a speed lower than that of the bowl, this structure causes the liquid to be smoothly accelerated and to smoothly .flow through the aperture 51 and on to the edge of the bowl through the holes 18 and down the passageways 17.

The separator shown and described in the drawings operates in the separation of nitroglycerin from its reaction mixture as follows. The mixture of mixed acid and nitroglycerin is introduced into the spinning separating chamber 15 through the inlet 16. The incoming mixture is accelerated during its travel across the bottom of the chamber and during its downward travel through the passageways 17. The mixture is forced downwardly and inwardly through the annulus 19 and flows smoothly over the intersection of the surface of the annulus 19 and the downwardly and outwardly inclined wall 20 of the separating chamber as shown in. Fig. 4. The components of the mixture now begin separating as they proceed down the wall 20. The heavier. mixed. acid, showniby thetheavy lines, proceeds to the outside of the bowl while the lighter nitroglycerin forms an inner layer shown by the light lines. The mixed acid exits through the passageways 23, 24 and 25 into the collector 26 and is withdrawn through outlet 27 and sent to the recovery and concentration steps. The lighter nitroglycerin is forced inwardly over the dam 21 and exits through passageways 28 intothe collector 29 from which it is removed through outlet 30; The separation achieved is highly efficient and the nitroglycerin removed from the separator is ready for the final soda wash and emulsification steps. It has been found that as compared to the 200-300 pounds of sensitive nitroglycerin present in the 'Biazzi system there is seldom more than from 25 pounds of sensitive nitroglycerin present in the separator, the collector or the line leading to the soda wash apparatus. It is, therefore, ap-

parent that the separator of the invention constitutes a 3 great advance in safety as compared to known methods of separation. Moreover, the centrifugal separators of the invention are comparatively small with respect to the massive separation equipment employed by the art and represent a .much smaller capital investment.

The optimum speed of rotation for each mixture of liquids to be separated will, of course, vary with the mixture itself and the desired capacity of the equipment.

The preferred material of construction for the separators and the collectors is stainless steel, although any other suitable material of construction may be employed as desired. It is also preferred. to employ stainless steel for the baffles such as shown in Fig. 3 which may desirably be employed to prevent splashing and otherwise enhance the smoothness of feed to the separator. The acceleration baflles shown in Fig. 2 are not essential and if employed are preferably made of a plastic such as Teflon or polyethylene.

Since modification of the centrifugal separators disclosed will be apparent to those skilled in the art and which will not depart from the scope of invention, it is intended that the invention be limited only by the scope of the appended claims.

What I claim and desire to protect by Letters Patent is:

l. A centrifugal separator for liquids having in combination a' bowlmounted to revolve about its vertical axis, means for-revolving the bowl, and collecting means for the separated liquid components, said bowl comprising a receiving chamber at the top thereof for receipt of the liquid feed, a plurality of spaced passageways extending. downwardly and outwardly through the wall of the bowl from a point adjacent the intersection of the bottom and the wall of the receiving chamber, a separating chamber disposed below the receiving chamber and in communication with the receiving chamber through the said passageways, a dam disposed at the bottom of the wall ofthe separatingchamber and extending substantially horizontally inwardly and then substantially vertically downwardly, an exit annulus for the heavier liquid component leading outwardly from the horizontal surface of the darn at points adjacent the intersection of the wall of the separating chamber and the horizontal surface of the dam, and a plurality of spaced exit conduits for thelighter liquid component leading outwardly from the verticalsurface of the dam at points adjacent the bottomof the separating chamber, said exit annulus and exit conduits for the liquid components being in communication with the said collecting means.

2. A centrifugal separator according to claim 1 in which the bowlfhas vanes formed on the wall of the receiving chamber as acceleration means for the incoming liquid feed.

3. A centrifugal separator according to claim 1 in which a stationary baffle plate is disposed in the receiving chamber between the inlet for liquid feed and the chamber wall with one edge thereof approaching the bottom of the chamber but being spaced therefrom to permitilow thereunder. 4. A centrifugal separator according to claim 1 contaming an annulus leading, downwardly and inwardly from said passageways to the wall of the bowl and wherein the wall of the separating chamber is inclined outwardly .and downwardly from the mouth of the said annulus. l i

5. A centrifugal separator according to claim 1 in which the interior of the bowl below the bottom of the receiving chamber is open.

6. A centrifugal separator according to claim 1 in which the bottom of the bowl and separating chamber is formed from a readily removable, force fitting, plastic 'ofthe liquid feed, a plurality of spaced passageways extending downwardly and outwardly through the wall of the bowl from a point adjacent the intersection of the bottom and the wall of thereceiving chamber, an annu- 5 lus leading downwardly and inwardly from the passageways through the wall of the bowl, a separating chamber disposed below the receiving chamber and in communication with the annulus, a dam disposed at the bottom of the wall of the separating chamber and extending substantially horizontally inwardly and then substantially vertically downwardly, an exit annulus for the heavier liquid component leading downwardly and outwardly from the horizontal surface of the darn at points adjacent the intersection of the wall of the separating chamber and the horizontal surface of the dam, and a plurality of spaced exit conduits for the lighter liquid component leading downwardly and outwardly from the substantially vertical surface of the darn at points adjacent the bottom of the separating chamber, said exit annulus and exit conduits for the liquid components being in communication with the said collecting means.

8. A centrifugal separator according to claim 7 in which the bowl has baflles formed on the wall of the receiving chamber as acceleration means for the incoming liquid feed.

9. A centrifugal separator according to claim 7 in outwardly and downwardly from the mouth of the annulus. I

11. A centrifugal separator according to claim 7 in which the interior of the bowl below the bottom of the receiving chamber is open.

12. A centrifugal separator according to claim 7 in which the bottom of the bowl and separating chamber is formed from a readily removable plastic plug.

References Cited in the file of this patent UNITED STATES PATENTS Shue Apr. 24, 1900 Shue Mar. 31, 1903 

